Multiple center hole abrasive disk



Aug. 3, 1954 s Shets-Sheet 1 Aiiorrzeys J- J. KUZMA ET AL 2,685,155 MULTIPLE CENTER HOLE ABRASIVE DISK Original Filed Ju1y 5, 1950 1954 J. J. KUZMA ET AL 2,685,155

MULTIPLE CENTER HOLE ABRASIVE DISK Original Filed July 5, 1950 5 Sheets-Sheet 2 1954 J. J. KUZMA ET AL I 2,685, 55

MULTIPLE CENTER HOLE ABRASIVE DISK Original Filed July 5, 1950 3 Sheets-Sheet 3 WMW 14550 mez/s Patented Aug. 3, 1954 UNITED STATES 2,685,155 MULTIPLE CENTER HOLE ABRASIVE DISK John J. Kuzma, St. Paul, Minn, Kenneth W. Kurtz, Cincinnati, Ohio, and Clifford A. Baker, St. Paul, Minn., assignors to Minnesota Mining & Manufacturing Company, St. Paul, Minn, a corporation of Delaware Continuation of application Serial N 0. 172,102,

July 5, 1950. This application April 28, 1951, Serial No. 223,544

12 Claims. (Cl. 51-195) This invention relates to abrasive discs and more particularly to the center holes with which abrasive discs are pierced to permit their attachment to machines that rotate the discs in an abrading operation.

Such machines usually comprise a relatively rigid circular back-up plate or pad against which the disc is placed abrasive side out. The plate or pad is a part of an assembly frequently called a sanding head, and is rotated by power means.

There are numerous means by which the disc can be held to the pad. In substantially all constructions, however, the center of the disc is pierced by a cylindrical member of a given diameter, such as the shank of an adapter nut, or a screw, or the spindle of the head mechanism. Consequently, the disc must have a center hole into which the said cylindrical member will fit. Most of the center holes heretofore known have been circular; they may also have the shape of a regular polygon (or even a square or an equilateral triangle) of such size that the sides of the polygon (or square or triangle) are tangent to the cylindrical member. The term cylindrical member as used herein embraces members whose cross section is something that merely approximates a circle, such as a polygon, as well as those whose cross section is a strict circle.

In sanding head constructions using an adapter nut, the shank of the adapter nut is usually cylindrical and is usually axially bored, the bore having inside threads for screwing the nut onto the power driven threaded spindle of the sanding head mechanism. In constructions using a screw to hold the disc on the pad, the sanding head spindle is axially bored and the bore has inside threads for receiving the screw.

Pads are frequently made with a depression in the central portion of their face so that, when screwed into place, the head of the adapter nut or the screw is below the working face of the abrasive disc.

Adapter nut shanks, or screws, or other cylindrical members that pierce the disc in the numerous types of sanding heads or other machines in which discs are used in abrading operations, vary in diameter in different machines.

Consequently, manufacturers and dealers in discs, in order to have a complete stock with which to meet the demands of the trade, have heretofore been required to stock a separate series of discs in each of the currently required sizes of center holes, in each of the numerous kinds and sizes of abrasive grits, in each of the kinds and sizes of disc backings.

It is therefore an objective of the present invention to reduce this multiplicity of types of abrasive discs by providing a central opening for abrasive discs that will permit a single disc to fit a plurality of sizes of adapter nuts or screws or other cylindrical holding members that pierce the center of the disc when the disc is mounted for use.

The invention provides a central opening which includes a series of tabs pointing toward the center. Cuts that extend transversely of the tabs, some or all of which may effect truncations of the tabs as hereinafter described, provide a center hole either of the circular or polygonal type, that will fit a plurality of sizes of disc holding members.

The invention provides a central opening characterized by cuts or slits along the boundary lines of each of a plurality of circles or polygons of differing sizes concentric with the disc, together with a plurality of radial slits which form tabs.

The invention provides a central opening which includes a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs pointing toward the center, a series of successive cuts that intersect the radial slits, the cuts being equidistant from the center and the series extending around the center, and a second series of successive cuts that intersect the radial slits, the cuts of the second series also being equidistant from the center and the second series extending around the center, the second series being at a greater distance from the center than the first. There may be more than two series.

Each series of cuts has the effect of forming a small circle around the center of the disc. The cuts may be arcuate and extend along the line of an exact circle that is concentric with the disc, or the cuts may be straight or angular and extend along the line of a polygon that is concentric with the disc.

As a matter of uniformity of nomenclature, all the radial cuts or slits are referred to herein as slits, and the cuts or slits that intersect them as cuts.

Illustrative examples are described below and shown in the accompanying drawings in which:

Figure l is a plan view of an abrasive disc equipped with a central opening of the circular type according to the present invention;

Figure 2 is an enlarged fragmentary plan view of the central portion of the disc of Figure 1;

Figures 3, 4 and 5 are fragmentary side elevations of the disc of Figure l with adapter nuts having cylindrical shanks of varying diameters, respectively, inserted in the center hole;

Figure 6 is a fragmentary plan view of an alternative form;

Figure 7 is a plan view of a furthermodification;

Figure 8 is an enlarged fragmentary plan view of the central portion of the disc of Figure "1;

Figures 9 and 10 are fragmentary side elevations of the disc of Figure 7 with adapter nuts having cylindrical shanks of varying diameters, respectively, inserted in the center hole;

Figure 11 is a fragmentary plan view of an alternative form of the disc of Figure 7; and

Figures 12 and 13 are plan views of central openings of the polygonal type.

Referring to the disc M of Figures 1 to 5, six radial slits l5 spaced an equal distance apart, extend outwardly from the center. These form a series of six tabs. Each alternate tab is cut off or truncated along the line N3 of a circle concentric with the disc, forming three relatively long tabs it. Each of the remaining tabs is truncated along the line ll of a larger concentric circle, forming three relatively short tabs ii.

The disc Hi thus has a plurality of spaced apart radial slits 15 that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs it. ll pointing toward the center; it also has a series of successive cuts it that intersect the radial slits Iii, the cuts 15 all being equidistant from the center and the series extending around the center; and it has a second series of successive cuts ll that intersect the radial slits 15, the cuts ['1 all being equidistant from the center and the series extending around the center, the second series being at a greater distance from the center than the first.

The disc l4 may also be described as having a plurality of spaced apart radial slits 15 that extend outwardly from the center toward the periphery of the disc to form a series of tabs [5, ll" pointing toward the center, and a plurality of circular cuts :5, ll intersecting the radial slits l5 and extending along the lines of each of a plurality of circles of differing sizes concentric with the disc.

The one disc 14 when so formed, can acco1nmodate an adapter nut 2G having a relatively large shank 2! (Figure 3), or an adapter nut 22 having a smaller shank 23 (Figure 4), or an adapter nut 24 having a still smaller shank 25 (Figure 5).

The locations of the peripheries of the shanks are indicated by the circular dotted lines 2! 23' and 25' in Figure 2.

When an adapter nut shank whose diameter is the same as that of the smaller circle 16, is inserted in the disc in preparation for mounting the disc on a sanding head, the tabs are not bent downwardly by the shank, but lie or extend adjacent the under surface of the head of the adapter (Figure 5). When larger adapters are used, however, the diameters of whose shanks range in size up to and including the size of the diameter of the larger circle H, such for example as the adapters 22 and 29 in Figures 4 and 3, the three tabs H5 are bent downwardly by the shank when the shank is inserted in the center hole of the disc. After such an adapter has been pressed into position in the disc with its head resting on the surface of the disc, it is then preferable to crease or fold the tabs along the circles 23 or 2|, as the case may be, so that the tabs l'c" lie snugly against the sides of the shank all the way up to where the shank meets the head of the adapter, as shown in Figures 4 and 3.

If desired, the radial slits l5 need not extend outwardly from the center beyond the larger circle ll. Such a construction is illustrated in Figure 6, and may be described as a disc havin a central opening whose outer limits l H lie along the line of a circle concentric with the disc, and a plurality of pointed tabs H5 in spaced relation to each other extending inwardly from the said circle, the tabs being truncated along the line H6 of a smaller concentric circle.

It will be seen that the one disc of Figures 1 to 5, can accommodate an adapter having a shank whose diameter is the same as the diameter of the smaller circle [5, or an adapter having a shank whose diameter is the same as the diameter of the larger circle IT, or adapters having shanks the sizes of whose diameters range between those two limits. The latter group, i. e., the intermediate sizes, is exemplified by the adapter shown in Figure 4.

The disc of Figure 6 is likewise adapted to accommodate shanks of the varying diameters described.

Referring now to the disc 28 of Figures 7, 8, 9 and 10, four radial slits 29 spaced an equal dis tance apart, extend outwardly from the center. These form a series of four tabs 38'. Each tab is truncated along the line 33 of a circle concentric with the disc, forming an aperture bounded by the said circle. Each tab is cut inwardly from its edges toward its center along the line 3! of a larger concentric circle.

The disc 28 thus has a plurality of spaced apart radial slits 29 that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs 30' pointing toward the center; it also has a series of successive cuts 39 that intersect the radial slits 29, the cuts 30 all being equidistant from the center and the series extending around the center; and it has a second series of successive cuts 31 that intersect the radial slits 29, the cuts 34 all being equidistant from the center and the series extending around the center, the second series being at a greater distance from the center than the first.

The disc 28 may also be described as having a plurality of spaced apart radial slits 29 that extend outwardly from the center toward the periphery of the disc to form a series of tabs 3Q pointing toward the center, and a plurality of circular cuts 3%, 3i intersecting the radial slits 29 and extending along the lines of each of a plurality of circles of different sizes concentric with the disc.

The one disc 28 when so formed, can accommodate an adapter nut 32 having a relatively large shank 33 (Figure 9) or an adapter nut 34 having a relatively small shank 35 (Figure 10). The location of the periphery of the large shank 33 is indicated by the dotted circular line 33' in Figure 8. The periphery of the small shank coincides substantially with the smaller circle 30, i. e., with the truncated ends of the tabs 32'.

When an adapter nut shank whose diameter is the same as that of the smaller circle 30, is inserted in the disc in preparation for mounting the disc on a sanding head, the tabs 39 are not bent downwardly by the shank, but lie or extend adjacent the under surface of the head of the adapted (Figure 1'0) But when an adapter having a shank whose diameter is the same as that of the larger circle 3!, is inserted, the tabs 30 are all bent downwardly by the shank when the shank is inserted in the center hole of the disc (Figure 9). After such an adapter has been pressed into position in the disc with its head resting on the surface of the disc, it is then preferable to crease or fold the tabs along the circle 33 so that the tabs lie snugly against the sides of the shank all the way up to where the shank meets the head of the adapter as shown in Figure 9.

If desired, the radial slits 29 need not extend outwardly beyond the larger circle 3|. Such a construction is shown in Figure 11, and may be described as a disc having a central opening whose outer limits I30 lie along the line of a circle concentric with the disc, a plurality of dis connected cuts |3| along the line of a larger concentric circle, and a plurality of radial slits I29 connecting the opening I30 with the cuts |3|.

Referring now to the disc 2M of Figure 12, six radial slits 2|5 spaced an equal distance apart, extend outwardly from the center. These form a series of six tabs. Each alternate tab is cut off or truncated along the line 2|6 of a hexagon h that is concentric with the disc, forming three relatively long tabs 2|6'. Each of the remaining tabs is truncated along the line 2 7 of a larger concentric hexagon h, forming three relatively short tabs 2".

The disc 2| 4 thus has a plurality of spaced apart radial slits 2| 5 that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs 2 6', 2 l 1 pointing toward the center; it also has a series of successive cuts 2| 6 that intersect the radial slits 2|5, the cuts 2 Hi all being equidistant from the center and the series extending around the center; and it has a second series of successive cuts 2|1 that intersect the radial slits 2l5, the cuts 2|'| all being equidistant from the center and the series extending around the center, the second series being at a greater distance from the center than the first.

The disc 2M may also be described as having a plurality of spaced apart radial slits 2|5 that extend outwardly from the center toward the periphery of the disc to form a series of tabs 2 l6, 2|1' pointing toward the center, and a plurality of cuts 2H5, 2|! intersecting the radial slits 2|5 and extending along the lines of each of a plurality of polygons of difiering sizes concentric with the disc.

Such a disc when so formed can accommodate the several sizes of cylindrical adapted nut shanks 2| 23 and 25, as does the disc It in the manner hereinbefore described, except that the edge of the center hole will here have the configuraton of a hexagon rather than a circle, with its straight sides making tangential contact with the cylindrical shanks at the center of each side, in the manner that the edge 2|! contacts the shank 2| and the edge 2 l6 contacts the shank 25 in Figure 12.

The outwardly extending radial slits 2 I5 may, if desired, stop short at the out 2||, to form a modification which relates to the center hole shown in Figure 12 in the same manner that the center hole of Figure 6 relates to the center hole of Figure 2.

Referring now to the disc 228 of Figure 13, four radial slits 229 spaced an equal distance apart, extend outwaardly from the center. These form a series of four tabs 239'. Each tab is truncated along the line 23|l239 of an octagon o concentric with the disc, forming an aperture bonded by the said octagon. Each tab is out inwardly from its edges toward its center along the boundary line 23| of a duodecagon d which is larger than the octagon 0 and concentric therewith.

The disc 228 thus has a plurality of spaced apart radial slits 229 that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs 230 pointing toward the 6 center; it also has a series of successive cuts 239 that intersect the radial slits 229, the cuts 239 all being equidistant from the center and the series extending around the center; and it has a second series of successive cuts 23| that intersect the radial slits 229, the cuts 23| all being equidistant from the center and the series extending around the center, the second series being at a greater distance from the center than the first.

The disc 228 may also be described as having a plurality of spaced apart radial slits 229 that extend outwardly from the center toward the periphery of the disc to form a series of tabs 230' pointing toward the center, and a plurality of cuts 239, 23| intersecting the radial slits 229 and extending along the lines of each of a plurality of polygons of difiering sizes concentric with the disc.

Such a disc when so formed can accommodate the two different sizes of the cylindrical adapter nut shanks 33 and 35, as does the disc 28 in the manner hereinbefore described, except that the edge of the center hole will here have the configuration of an octagon or a duodecagon (as the case may be) rather than a circle, with its straight sides making tangential contact with the cylindrical shanks at the center of each side, in the manner that the edge 23| is shown contacting the shank 39 and the edge 230 is shown contacting the shank 35 in Figure 13.

If desired, the radial slits 229 which extend outwardly from the center, may stop short at the cuts 23| to form a modification which relates to the center hole shown in Figure 13 in the same manner that the center hole of Figure 11 relates to that shown in Figure 8.

Discs such as that shown in Figures 1 to 5, have been constructed having the following dimensions: diameter, 6"; length of the radial slits l5 (which are 60 apart) measured from the circle I6, diameter of the circle l6, diameter of the circle I1, 1". Such discs will accommodate cylindrical disc-holding members having diameters ranging from to 1".

Discs such as that shown in Figures 7 to 10, have been constructed having the following dimensions: diameter, 6"; length of the radial slits 29 (Which are apart) measured from the circle 39, 7 diameter of the circle 30, /3"; diameter of the circle 3|, 1". Such discs will accommodate cylindrical disc-holding members having diameters of or 1".

Discs such as that shown in Figure 12 have been constructed having the following dimensions: diameter, 5"; length of the radial slits 2|5 (which are 60 apart) measured from the line 2H5, 9/ distance along the radial slits 2|5 from the cut 2|6 to the out 2|'|, f length of the cuts 2|6. approximately length of the cuts 2| 1, diameter of the circle 25, 4"; diameter of the circle 2|, 1".

It will of course be understood that the above dimensions are only exemplary. They may vary widely within the scope of the invention.

The precise patterns of the slits and cuts shown herein are also exemplary, and may vary widely within the scope of the invention.

The circular and the polygonal type of opening may be combined in a single disc, if desired. For example, the smaller or inner series of cuts may follow the line of the octagon o as in Figure 13 while the larger or outer series of cuts may follow the line of the circle 3| as in Figure 8.

It is preferred that a cut or a slit pierce the disc. If desired, however, scoring or perforations or a combination of the two may replace a cut or a slit for all or a part of its length.

For example, the cuts 31, I34 or 23k may instead be scores or a series of perforations. If such a disc is used on a sanding head whose adapter nut has a large shank such as the shank 33, then the tabs are either bent along the score or perforation lines, or, the score or perforation lines are first broken through by the operator to form the illustrated cuts 31, 13! or 231 that pierce the disc, and the tabs then bent.

It will be seen that when provided with a corn tral opening which, according to the present invention, i characterized by a plurality of series of successive cuts extending around the center, the several series being at difierent distances from the center, together with a plurality of radial slits intersecting the cuts, a single disc can accommodate a number of different sized cylindrical holding members. The disc can accommodate as many different sizes of cylindrical holding members as there are series of cuts, and in some constructions, such for example as those of Figures 1 to 6 and 12, any intermediate size between the sizes of the largest and smallest series, can be accommodated, as well.

This is a continuation of our co-pending appli cation Serial No. 172,102 filed July 5,1959, which latter is a continuation-in-part of our copending application Serial No. 160,752, filed May 8, 1950, both now abandoned.

We claim:

1. An abrasive disc having a central opening of the character described, the said opening comprising a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs pointing toward the center, a series of successive cuts that intersect the radial slits, the cuts being equidistant from the center and the series extending around the center, and a second. series of successive cuts that intersect the radial slits, the cuts of the second series also being equidistant i'rom the center and the second. series extending around the center, the second series being at a greater distance from the center than the first.

2. An abrasive disc according to claim 1 having a central opening of the character described.

the said opening comprising a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a plurality of tabs pointing toward the center; each alternate tab being truncated at a given distance from the center of the disc to form a series of tabs of equal length, the remaining tabs being truncated at a greater distance from the center of the disc to form a second series of tabs equal in length to each other but shorter than the first series.

3. An abrasive disc according to claim 1, having a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a series of tabs pointtoward the center, and a plurality of circular cuts intersecting the said radial slits and extending along the lines of each of a plurality of circles of diilering sizes concentric with the disc.

4. An abrasive disc according to claim 3, having a central opening, the outer limits of the opening lying along the line of a circle concentric vith the disc, and a plurality of pointed tabs in spaced relation to each other extending inwardly from the said circle, the tabs being truncated along the line of a smaller concentric circle.

5. An abrasive disc according to claim 3, havinga central opening whose outer limits lie along the line of a circle concentric with the disc, a plurality of disconnected cuts along the line of a larger concentric circle, and a plurality of radial slits connecting the opening with the cuts.

6. An abrasive disc according to claim 4, having a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a series of tabs pointing toward the center, the tabs being truncated, each alternate tab being truncated along the line of a circle concentric with the disc, the remaining tabs being truncated along the line of a larger concentric circle.

7. An abrasive disc according to claim 5, having a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a series of tabs point ing toward the center, the tabs being truncated along the line of a circle concen ric with the disc, and being cut inwardly from each of their respective edges toward their centers along the line of a larger concentric circle.

3. An abrasive disc according to claim 1, having a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a series of tabs pointing toward the center, and a plurality of cuts intersecting the said radial slits and extending along the lines of each of a plurality of polygons of differing sizes concentric with the disc.

9. An abrasive disc according to claim 8, having a central opening, the outer limits of the opening lying along the line of a polygon concentric with the disc, and a plurality of pointed tabs in spaced relation to each other extending inwardly from the said polygon, the tabs being truncated along the line of a smaller concentric polygon.

10. An abrasive disc according to claim 9, having a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a series of tabs pointing toward the center, the tabs being truncated,

each alternate tab being truncated along the line of a polygon concentric with the disc, the remaining tabs being truncated along the line of a larger concentric polygon.

11. An abrasive disc according to claim 8, having a central opening whose outer limits lie along the line of a polygon concentric with the disc. a plurality of disconnected cuts along the line of a larger concentric polygon, and a plurality of radial slits connecting the opening with the cuts.

12. An abrasive disc according to claim 11, having a plurality of spaced apart radial slits that extend outwardly from the center toward the periphery of the disc to form a series of tabs pointing toward the center, the tabs being truncated along the line of a polygon concentric with the disc, and being out inwardly from each of their respective edges toward their centers along the line of a larger concentric polygon.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 407,249 Rogers July 16. 1889 533,828 Perry Feb. 5. 1895 802,136 Busfield Oct. 17, 1905 1,176,001 Stewart Mar. 21, 1916 1,693,163 Schacht Nov. 27, 1928 1,749,709 Loveland Mar. 4, 1930 

